Assigned Protection Factors, 50122-50192 [06-6942]

Agencies

• DEPARTMENT OF LABOR
• Occupational Safety and Health Administration

[Federal Register Volume 71, Number 164 (Thursday, August 24, 2006)]
[Rules and Regulations]
[Pages 50122-50192]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-6942]



[[Page 50121]]

-----------------------------------------------------------------------

Part II





Department of Labor





-----------------------------------------------------------------------



Occupational Safety and Health Administration



-----------------------------------------------------------------------



29 CFR Parts 1910, 1915, and 1926



Assigned Protection Factors; Final Rule

Federal Register / Vol. 71, No. 164 / Thursday, August 24, 2006 / 
Rules and Regulations

[[Page 50122]]


-----------------------------------------------------------------------

DEPARTMENT OF LABOR

Occupational Safety and Health Administration

29 CFR Parts 1910, 1915, and 1926

[Docket No. H049C]
RIN 1218-AA05


Assigned Protection Factors

AGENCY: Occupational Safety and Health Administration (OSHA), 
Department of Labor.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: In this final rule, OSHA is revising its existing Respiratory 
Protection Standard to add definitions and requirements for Assigned 
Protection Factors (APFs) and Maximum Use Concentrations (MUCs). The 
revisions also supersede the respirator selection provisions of 
existing substance-specific standards with these new APFs (except for 
the respirator selection provisions of the 1,3-Butadiene Standard).
    The Agency developed the final APFs after thoroughly reviewing the 
available literature, including chamber-simulation studies and 
workplace protection factor studies, comments submitted to the record, 
and hearing testimony. The final APFs provide employers with critical 
information to use when selecting respirators for employees exposed to 
atmospheric contaminants found in general industry, construction, 
shipyards, longshoring, and marine terminal workplaces. Proper 
respirator selection using APFs is an important component of an 
effective respiratory protection program. Accordingly, OSHA concludes 
that the final APFs are necessary to protect employees who must use 
respirators to protect them from airborne contaminants.

DATES: The final rule becomes effective November 22, 2006.

ADDRESSES: In compliance with 28 U.S.C. 2212(a), the Agency designates 
Joseph M. Woodward, the Associate Solicitor for Occupational Safety and 
Health, Office of the Solicitor, Room S-4004, U.S. Department of Labor, 
200 Constitution Avenue, NW., Washington, DC 20210, as the recipient of 
petitions for review of this rulemaking.

FOR FURTHER INFORMATION CONTACT: For technical inquiries regarding this 
final rule, contact Mr. John E. Steelnack, Directorate of Standards and 
Guidance, Room N-3718, OSHA, U.S. Department of Labor, 200 Constitution 
Ave., NW., Washington, DC 20210; telephone (202) 693-2289 or fax (202) 
693-1678. For general inquiries regarding this final standard contact 
Kevin Ropp, OSHA Office of Public Affairs, Room N-3647, U.S. Department 
of Labor, 200 Constitution Ave., NW., Washington, DC 20210 (telephone 
(202) 693-1999). Copies of this Federal Register notice are available 
from the OSHA Office of Publications, Room N-3101, U.S. Department of 
Labor, 200 Constitution Ave., NW., Washington, DC 20210 (telephone 
(202) 693-1888). For an electronic copy of this notice, as well as news 
releases and other relevant documents, go to OSHA's Web site (https://
www.osha.gov), and select ``Federal Register,'' ``Date of 
Publication,'' and then ``2006''.

SUPPLEMENTARY INFORMATION:

I. General

A. Table of Contents

    The following Table of Contents identifies the major preamble 
sections of this final rule and the order in which they are presented:

I. General
    A. Table of Contents
    B. Glossary
II. Events Leading to the Final Standard
    A. Regulatory History of APFs
    B. Non-Regulatory History of APFs
    C. Need for APFs
III. Methodology for Developing APFs for Respirators
    A. Introduction
    B. Background
    C. Methodology, Data, and Studies on Filtering Facepieces and 
Elastomerics
    D. Alternative Approaches
    E. Updated Analyses
    F. Summary of Studies Submitted During the Rulemaking
IV. Health Effects
V. Summary of the Final Economic Analysis and Initial Regulatory 
Flexibility Analysis
    A. Introduction
    B. The Rule and Affected Respirator Users
    C. Compliance Costs
    D. Benefits
    E. Economic Feasibility
    F. Economic Impacts to Small Entities
VI. Summary and Explanation of the Final Standard
    A. Definition of Assigned Protection Factor
    B. APF Provisions
    C. Assigned Protection Factors for Specific Respirator Types
    1. APF for Quarter Mask Air-Purifying Respirators
    2. APF for Half Mask Air-Purifying Respirators
    3. APF for Full Facepiece Air-Purifying Respirators
    4. APF for Powered Air-Purifying Respirators (PAPRs)
    5. APF for Supplied-Air Respirators (SARs)
    6. APF for Self-Contained Breathing Apparatuses (SCBAs)
    D. Definition of Maximum Use Concentration
    E. MUCs for Mixtures and Hazard Ratios
    F. MUC Provisions
    G. Superseding the Respirator Selection Provisions of Substance-
Specific Standards in Parts 1910, 1925, and 1926
VII. Procedural Determinations
    A. Legal Considerations
    B. Paperwork Reduction Act
    C. Federalism
    D. State Plans
    E. Unfunded Mandates
    F. Applicability of Existing Consensus Standards
List of Subjects in 29 CFR Parts 1910, 1915, and 1926
Authority and Signature
Amendments to Standards

B. Glossary
    This glossary specifies the terms represented by acronyms, and 
provides definitions of other terms, used frequently in the preamble to 
the final rule. This glossary does not change the legal requirements in 
this final rule, nor is it intended to impose new regulatory 
requirements on the regulated community.
1. Acronyms
ACGIH: American Conference of Governmental Industrial Hygienists
AIHA: American Industrial Hygiene Association
ANSI: American National Standards Institute
APF: Assigned Protection Factor
APR: Air-purifying respirator
Ci: Concentration measured inside the respirator facepiece
Co: Concentration measured outside the respirator
DOP: Dioctylphthalate (see definition below)
DFM: Dust, fume, and mist filter
EPF: Effective Protection Factor (see definition below under 
``Protection factor study'')
HEPA: High efficiency particulate air filter (see definition below)
IDLH: Immediately dangerous to life or health (see definition below)
LANL: Los Alamos National Laboratory
LASL: Los Alamos Scientific Laboratory
LLNL: Lawrence Livermore National Laboratory
MSHA: Mine Safety and Health Administration
MUC: Maximum Use Concentration
NFPA: National Fire Protection Association
NIOSH: National Institute for Occupational Safety and Health
NRC: Nuclear Regulatory Commission
OSHA: Occupational Health and Safety Administration
OSH Act: The Occupational Safety and Health Act of 1970 (29 U.S.C. 655, 
657, 665).
PAPR: Powered air-purifying respirator (see definition below)

[[Page 50123]]

PEL: Permissible Exposure Limit
PPF: Program Protection Factor (see definition below under ``Protection 
factor study'')
QLFT: Qualitative fit test (see definition below)
QNFT: Quantitative fit test (see definition below)
RDL: Respirator Decision Logic (see definition below)
REL: Recommended Exposure Limit (see definition below)
SAR: Supplied-air (or airline) respirator (see definition below)
SCBA: Self-contained breathing apparatus (see definition below)
WPF: Workplace Protection Factor (see definition below under 
``Protection factor study'')
TLV: Threshold Limit Value (see definition below)
SWPF: Simulated Workplace Protection Factor (see definition below under 
``Protection factor study'')
2. Definitions
    Terms followed by an asterisk (*) refer to definitions that can be 
found in paragraph (b) (``Definitions'') of OSHA's Respiratory 
Protection Standard (29 CFR 1910.134).
    Air-purifying respirator*: A respirator with an air-purifying 
filter, cartridge, or canister that removes specific air contaminants 
by passing ambient air through the air-purifying element.
    Atmosphere-supplying respirator*: A respirator that supplies the 
respirator user with breathing air from a source independent of the 
ambient atmosphere, and includes SARs and SCBA units.
    Canister or cartridge*: A container with a filter, sorbent, or 
catalyst, or combination of these items, which removes specific 
contaminants from the air passed through the container.
    Continuous flow respirator: An atmosphere-supplying respirator that 
provides a continuous flow of breathable air to the respirator 
facepiece.
    Demand respirator*: An atmosphere-supplying respirator that admits 
breathing air to the facepiece only when a negative pressure is created 
inside the facepiece by inhalation.
    Dioctylphthalate (DOP): An aerosolized agent used for quantitative 
fit testing.
    Elastomeric: A respirator facepiece made of a natural or synthetic 
elastic material such as natural rubber, silicone, or EPDM rubber.
    Filter or air-purifying element*: A component used in respirators 
to remove solid or liquid aerosols from the inspired air.
    Filtering facepiece (or dust mask)*: A negative pressure 
particulate respirator with a filter as an integral part of the 
facepiece or with the entire facepiece composed of the filtering 
medium.
    Fit factor*: A quantitative estimate of the fit of a particular 
respirator to a specific individual and typically estimates the ratio 
of the concentration of a substance in ambient air to its concentration 
inside the respirator when worn.
    Fit test*: The use of a protocol to qualitatively or quantitatively 
evaluate the fit of a respirator on an individual.
    Helmet*: A rigid respiratory inlet covering that also provides head 
protection against impact and penetration.
    High-efficiency particulate air filter (HEPA)*: A filter that is at 
least 99.97% efficient in removing monodisperse particles of 0.3 
micrometers in diameter. The equivalent NIOSH 42 CFR part 84 
particulate filters are the N100, R100, and P100 filters.
    Hood*: A respiratory inlet covering that completely covers the head 
and neck and may also cover portions of the shoulders and torso.
    Immediately dangerous to life or health (IDLH)*: An atmosphere that 
poses an immediate threat to life, would cause irreversible adverse 
health effects, or would impair an individual's ability to escape from 
a dangerous atmosphere.
    Loose-fitting facepiece*: A respiratory inlet covering that is 
designed to form a partial seal with the face.
    Negative pressure respirator (tight-fitting)*: A respirator in 
which the air pressure inside the facepiece is negative during 
inhalation with respect to the ambient air pressure outside the 
respirator.
    Permissible Exposure Limit (PEL): An occupational exposure limit 
specified by OSHA.
    Positive pressure respirator*: A respirator in which the pressure 
inside the respiratory inlet covering exceeds the ambient air pressure 
outside the respirator.
    Powered air-purifying respirator (PAPR)*: An air-purifying 
respirator that uses a blower to force the ambient air through air-
purifying elements to the inlet covering.
    Pressure demand respirator*: A positive pressure atmosphere-
supplying respirator that admits breathing air to the facepiece when 
the positive pressure is reduced inside the facepiece by inhalation.
    Protection factor study: A study that determines the protection 
provided by a respirator during use. This determination generally is 
accomplished by measuring the ratio of the concentration of an airborne 
contaminant (e.g., hazardous substance) outside the respirator (Co) to 
the concentration inside the respirator (Ci) (i.e., Co/Ci). Therefore, 
as the ratio between Co and Ci increases, the protection factor 
increases, indicating an increase in the level of protection provided 
to employees by the respirator. Four types of protection factor studies 
are:
    Effective Protection Factor (EPF) study: A study, conducted in the 
workplace, that measures the protection provided by a properly 
selected, fit-tested, and functioning respirator when used 
intermittently for only some fraction of the total workplace exposure 
time (i.e., sampling is conducted during periods when respirators are 
worn and not worn). EPFs are not directly comparable to WPF values 
because the determinations include both the time spent in contaminated 
atmospheres with and without respiratory protection; therefore, EPFs 
usually underestimate the protection afforded by a respirator that is 
used continuously in the workplace.
    Program Protection Factor (PPF) study: A study that estimates the 
protection provided by a respirator within a specific respirator 
program. Like the EPF, it is focused not only on the respirator's 
performance, but also the effectiveness of the complete respirator 
program. PPFs are affected by all factors of the program, including 
respirator selection and maintenance, user training and motivation, 
work activities, and program administration.
    Workplace Protection Factor (WPF) study: A study, conducted under 
actual conditions of use in the workplace, that measures the protection 
provided by a properly selected, fit-tested, and functioning 
respirator, when the respirator is worn correctly and used as part of a 
comprehensive respirator program that is in compliance with OSHA's 
Respiratory Protection Standard at 29 CFR 1910.134. Measurements of Co 
and Ci are obtained only while the respirator is being worn during 
performance of normal work tasks (i.e., samples are not collected when 
the respirator is not being worn). As the degree of protection afforded 
by the respirator increases, the WPF increases.
    Simulated Workplace Protection Factor (SWPF) study: A study, 
conducted in a controlled laboratory setting and in which Co and Ci 
sampling is performed while the respirator user performs a series of 
set exercises. The laboratory setting is used to control many of the 
variables found in workplace studies, while the exercises simulate the 
work activities of respirator users. This type of study is designed to 
determine the optimum

[[Page 50124]]

performance of respirators by reducing the impact of sources of 
variability through maintenance of tightly controlled study conditions.
    Qualitative fit test (QLFT)*: A pass/fail fit test to assess the 
adequacy of respirator fit that relies on the individual's response to 
the test agent.
    Quantitative fit test (QNFT)*: An assessment of the adequacy of 
respirator fit by numerically measuring the amount of leakage into the 
respirator.
    Recommended Exposure Limit (REL): An occupational exposure level 
recommended by NIOSH.
    Respirator Decision Logic (RDL): Respirator selection guidance 
developed by NIOSH that contains a set of respirator protection 
factors.
    Self-contained breathing apparatus (SCBA)*: An atmosphere-supplying 
respirator for which the breathing air source is designed to be carried 
by the user.
    Supplied-air respirator (or airline) respirator (SAR)*: An 
atmosphere-supplying respirator for which the source of breathing air 
is not designed to be carried by the user.
    Threshold Limit Value (TLV): An occupational exposure level 
recommended by ACGIH.
    Tight-fitting facepiece*: A respiratory inlet covering that forms a 
complete seal with the face.

II. Events Leading to the Final Standard

A. Regulatory History of APFs

    Congress established the Occupational Safety and Health 
Administration (OSHA) in 1970, and gave it the responsibility for 
promulgating standards to protect the health and safety of American 
workers. As directed by the OSH Act, the Agency adopted existing 
Federal standards and national consensus standards developed by various 
organizations such as the NFPA and ANSI. The ANSI standard Z88.2-1969, 
``Practices for Respiratory Protection,'' was the basis of the first 
six sections (permissible practice, minimal respirator program, 
selection of respirators, air quality, use, maintenance and care) of 
OSHA's Respiratory Protection Standard (29 CFR 1910.134) adopted in 
1971. The seventh section was a direct, complete incorporation of ANSI 
Standard K13.1-1969, ``Identification of Gas Mask Canisters.''
    The Agency promulgated an initial respiratory protection standard 
for the construction industry (29 CFR 1926.103) in April 1971. On 
February 9, 1979, OSHA formally applied 29 CFR 1910.134 to the 
construction industry (44 FR 8577). Federal agencies that preceded OSHA 
developed the original maritime respiratory protection standards in the 
1960s (e.g., Section 41 of the Longshore and Harbor Worker Compensation 
Act). The section designations adopted by OSHA for these standards, and 
their original promulgation dates, are: Shipyards--29 CFR 1915.82, 
February 20, 1960 (25 FR 1543); Marine Terminals--29 CFR 1917.82, March 
27, 1964 (29 FR 4052); and Longshoring--29 CFR 1918.102, February 20, 
1960 (25 FR 1565). OSHA incorporated 29 CFR 1910.134 by reference into 
its Marine Terminal standards (Part 1917) on July 5, 1983 (48 FR 
30909). The Agency updated and strengthened its Longshoring and Marine 
Terminal standards in 1996 and 2000, and these standards now 
incorporate 29 CFR 1910.134 by reference.
    Under the Respiratory Protection Standard that OSHA initially 
adopted, employers were required to follow the guidance of the Z88.2-
1969 ANSI standard to ensure proper selection of respirators. 
Subsequently, OSHA published an Advance Notice of Proposed Rulemaking 
(``ANPR'') to revise the Respiratory Protection Standard on May 14, 
1982 (47 FR 20803). Part of the impetus for this notice was the 
Agency's inclusion of new respirator requirements in the comprehensive 
substance-specific standards promulgated under section (6)(b) of the 
OSH Act, e.g., fit testing protocols, respirator selection tables with 
assigned protection factors, use of PAPRs, changing filter elements 
whenever an employee detected an increase in breathing resistance, and 
referring employees with breathing difficulties, either at fit testing 
or during routine respirator use, to a physician trained in pulmonary 
medicine (see, e.g., 29 CFR 1910.1025 (OSHA's Lead Standard)). The 
respirator provisions in these substance-specific standards reflected 
advances in respirator technology and changes in related guidance 
documents that were state-of-the-art information at the time when OSHA 
published these substance-specific standards. These standards 
recognized that effective respirator use depends on a comprehensive 
respiratory protection program that includes the use of APFs.
    In the 1982 ANPR, OSHA sought information on the effectiveness of 
its current Respiratory Protection Standard, the need to revise the 
standard, and recommendations regarding what revisions should be made. 
The 1982 ANPR referenced the ANSI Z88.2-1980 standard on respiratory 
protection with its table of protection factors, the 1976 report by Ed 
Hyatt from LASL titled ``Respiratory Protection Factors'' (Ex. 2), and 
the RDL developed jointly by OSHA and NIOSH, as revised in 1978 (Ex. 9, 
Docket No. H049). The 1982 ANPR asked for comments on how OSHA should 
use protection factors. The Agency received 81 responses to this 
inquiry. The commenters generally supported revising OSHA's Respiratory 
Protection Standard, and provided recommendations regarding approaches 
for including a table of protection factors (Ex. 15).
    On September 17, 1985, OSHA announced the availability of a 
preliminary draft of the proposed Respiratory Protection Standard. This 
preproposal draft standard included a discussion of the public comments 
received in response to the 1982 ANPR, and OSHA's analysis of revisions 
needed in the Respiratory Protection Standard to address up-to-date 
respiratory protection. The Agency received 56 responses from 
interested parties (Ex. 36), which OSHA carefully reviewed in 
developing the proposed rule.
    On November 15, 1994, OSHA published the proposed rule to revise 29 
CFR 1910.134, and provided notice of an informal public hearing on the 
proposal (59 FR 58884). The Agency convened the informal public hearing 
on June 6, 1995. In response to the comments OSHA received on the 
proposal, the Agency proceeded to develop APFs. On June 15, 1995, as 
part of the public hearing, OSHA held a one-day panel discussion by 
respirator experts on APFs. The discussion included measuring 
respirator performance in WPF and SWPF studies, the variability of data 
from these studies, and setting APFs for various types of respirators 
that protect employees across a wide variety of workplaces and exposure 
conditions.
    OSHA also reopened the rulemaking record for the revised 
Respiratory Protection Standard on November 7, 1995 (60 FR 56127), 
requesting comments on a study performed for OSHA by Dr. Mark Nicas 
titled ``The Analysis of Workplace Protection Factor Data and 
Derivation of Assigned Protection Factors'' (Ex. 1-156). This study, 
which the Agency placed in the rulemaking docket on September 20, 1995, 
addressed the use of statistical modeling for determining respirator 
APFs. OSHA received 12 comments on the Nicas report. This report, and 
the comments received in response to it, convinced OSHA that more 
information would be necessary before the Agency could resolve the 
complex issues regarding how to establish APFs,

[[Page 50125]]

including what methodology to use in analyzing existing protection 
factor studies. (See Section IV. Methodology for Developing Assigned 
Protection Factors in the June 6, 2003 NPRM, 68 FR 34044, for a 
detailed discussion of the Nicas report and the comments OSHA 
received.)
    OSHA published the final, revised Respiratory Protection Standard, 
29 CFR 1910.134, on January 8, 1998 (63 FR 1152). The standard contains 
worksite-specific requirements for program administration, procedures 
for respirator selection, employee training, fit testing, medical 
evaluation, respirator use, and other provisions. However, OSHA 
reserved the sections of the final standard related to APFs and MUCs 
pending further rulemaking (see 63 FR 1182 and 1203). The Agency stated 
that, until a future rulemaking on APFs is completed:

    [Employers must] take the best available information into 
account in selecting respirators. As it did under the previous 
[Respiratory Protection] standard, OSHA itself will continue to 
refer to the [APFs in the 1987 NIOSH RDL] in cases where it has not 
made a different determination in a substance specific standard. (63 
FR 1163)

The Agency subsequently established a separate docket (i.e., H049C) for 
the APF rulemaking. This docket includes copies of material related to 
APFs that previously were placed in the docket (H049) for the revised 
Respiratory Protection Standard. The APF rulemaking docket also 
contains other APF-related materials, studies, and data that OSHA 
obtained after it promulgated the final Respiratory Protection Standard 
in 1998.
    On June 6, 2003, the Agency published in the Federal Register an 
NPRM titled ``Assigned Protection Factors; Proposed Rule'' (68 FR 
34036) that contained proposed definitions for APFs and MUCs, a 
proposed Table 1 with APFs for the various respirator classes, and 
proposed revisions to the APF provisions and tables in OSHA's 
substance-specific standards. The NPRM announced that OSHA would be 
holding an informal public hearing in Washington, DC on the proposal. 
The public hearings were held over three days, from January 28-30, 
2004. OSHA received extensive pre-hearing comments (Exs. 9-1 through 9-
43 and 10-1 through 10-60), written hearing testimony (Exs. 16-1 
through 16-25), post-hearing comments (Exs. 17-1 through 17-12), and 
post-hearing briefs (Exs. 18-1 through 18-9 and 19-1 through 19-8). 
Transcripts of the public hearings also were made and added to the APF 
Docket (Exs. 16-23-1, 16-23-2, and 16-23-3). It is from these public 
comments, exhibits, hearing transcript, and post-hearing submissions 
that OSHA has prepared these final APF and MUC provisions and revisions 
to substance-specific standards.

B. Non-Regulatory History of APFs

    In 1965, the Bureau of Mines published ``Respirator Approval 
Schedule 21B,'' which contained the term ``protection factor'' as part 
of its approval process for half mask respirators (for protection up to 
10 times the TLV) and full facepiece respirators (for protection up to 
100 times the TLV). The Bureau of Mines based these protection factors 
on quantitative fit tests, using DOP, that were conducted on six male 
test subjects performing simulated work exercises.
    The Atomic Energy Commission (AEC) published proposed protection 
factors for respirators in 1967, but later withdrew them because 
quantitative fit testing studies, which the AEC used to determine APFs, 
were available for some, but not all, types of respirators. To address 
this shortcoming, the AEC sponsored respirator performance studies at 
LASL, starting in 1969.
    ANSI standard Z88.2-1969, which OSHA adopted by reference in 1971, 
did not contain APFs for respirator selection. Nevertheless, this ANSI 
standard recommended that ``due consideration be given to potential 
inward leakage in selecting devices,'' and contained a list of the 
various respirators grouped according to the expected quantity of 
leakage into the facepiece during routine use.
    In 1972, NIOSH and the Bureau of Mines published new approval 
schedules for respiratory protection under 30 CFR 11. However, these 
new approval schedules did not include provisions for determining 
facepiece leakage as part of the respirator certification process.
    NIOSH sponsored additional respirator studies at LASL, beginning in 
1971, that used quantitative test systems to measure the overall 
performance of respirators. In a 1976 report titled ``Respirator 
Protection Factors'', Edwin C. Hyatt of LASL included a table of 
protection factors for: single-use dust respirators; quarter mask, half 
mask, and full facepiece air-purifying respirators; and SCBAs (Ex. 2). 
Hyatt based these protection factors on data from DOP and sodium 
chloride quantitative fit test studies performed at LASL on these 
respirators between 1970 and 1973. The table also contained recommended 
protection factors for respirators that had no performance test data. 
Hyatt based these recommended protection factors on the judgment and 
experience of LASL researchers, as well as extrapolations from 
available facepiece leakage data for similar respirators. For example, 
Hyatt assumed that performance data for SCBAs operated in the pressure-
demand mode could be used to represent other (non-tested) respirators 
that maintain positive pressure in the facepiece, hood, helmet, or suit 
during inhalation. In addition, Hyatt recommended in his report that 
NIOSH continue testing the performance of respirators that lacked 
adequate fit test data. To increase the database, Hyatt used a 
representative 35-person test panel to conduct quantitative fit tests 
from 1974 to 1978 on all air-purifying particulate respirators approved 
by the Bureau of Mines and NIOSH.
    In August 1975, the Joint NIOSH-OSHA Standards Completion Program 
published the RDL (Ex. 25-4, Appendix F, Docket No. H049). The RDL 
contained a table of protection factors that were based on quantitative 
fit testing performed at LASL and elsewhere, as well as the expert 
judgment of the RDL authors. In 1978, NIOSH updated the RDL specifying 
the following protection factors:

5 for single-use respirators;
10 for half mask respirators with DFM or HEPA filters;
50 for full facepiece air-purifying respirators with HEPA filters or 
chemical cartridges;
1,000 for PAPRs with HEPA filters;
1,000 for half mask SARs operated in the pressure-demand mode;
2,000 for full facepiece SARs operated in the pressure-demand mode; and
10,000 for full facepiece SCBAs operated in the pressure-demand mode.

    ANSI's Respiratory Protection Subcommittee (``Subcommittee'') 
decided to revise Z88.2-1969 in the late 1970s. During its 
deliberations, the Subcommittee conducted an extensive discussion 
regarding the role of respirator protection factors in an effective 
respiratory protection program. As a result, the Subcommittee decided 
to add an APF table to the revised standard. In May 1980, ANSI 
published the revision as Z88.2-1980 which contained the first ANSI 
Z88.2 respirator protection factor table (Ex. 10, Docket H049). The 
ANSI Subcommittee based the table on Hyatt's protection factors, which 
it updated using results from fit testing studies performed at LANL and 
elsewhere since 1973. For example, the protection factor for full 
facepiece air-purifying particulate respirators was 100 when 
qualitatively fit tested, or 1,000 when equipped with

[[Page 50126]]

HEPA filters and quantitatively fit tested. The table consistently gave 
higher protection factors to tight-fitting facepiece respirators when 
employers performed quantitative fit testing rather than qualitative 
fit testing. The ANSI Subcommittee concluded that PAPRs (with any 
respiratory inlet covering), atmosphere-supplied respirators (in either 
a continuous flow or pressure-demand mode), and pressure-demand SCBAs 
required no fit testing because they operated in a positive-pressure 
mode. ANSI assigned high protection factors to these respirators, but 
limited their use to concentrations below the IDLH values. Pressure-
demand SCBAs and combination continuous flow or pressure-demand airline 
respirators with escape provisions for use in IDLH atmospheres were 
assigned protection factors of 10,000 plus.
    In response to a complaint to NIOSH that the PAPRs used in a 
workplace did not appear to provide the expected protection factor of 
1,000, Myers and Peach of NIOSH conducted a WPF study during silica-
bagging operations. Myers and Peach tested half mask and full facepiece 
PAPRs under these conditions, and found protection factors that ranged 
from 16 to 215. They published the results of their study in 1983 
(Ex.1-64-46). The results of this study led NIOSH and other 
researchers, as well as respirator manufacturers, to perform additional 
WPF studies on PAPRs and other respirators.
    NIOSH revised its RDL in 1987 (Ex. 1-54-437Q) to address advances 
in respirator technology and testing. The revision retained many of the 
provisions of the 1978 RDL, but also lowered the APFs for other 
respirators based on NIOSH's WPF studies. For example, the APFs were 
lowered for the following respirator classes: PAPRs with a loose-
fitting hood or helmet (reduced to 25); PAPRs with a tight-fitting 
facepiece and a HEPA filter (lowered to 50); supplied-air continuous 
flow hoods or helmets (decreased to 25); and supplied-air continuous 
flow tight-fitting facepiece respirators (reduced to 50).
    In August 1992, ANSI again revised its Z88.2 Respiratory Protection 
Standard (Ex. 1-50). The ANSI Z88.2-1992 standard contained a revised 
APF table, based on the Z88.2 Subcommittee's review of available 
protection factor studies. In a report describing the revised standard 
(Ex. 1-64-423), Nelson, Wilmes, and daRoza described the rationale used 
by the ANSI Subcommittee in setting APFs:

    If WPF studies were available, they formed the basis for the 
[APF] number assigned. If no such studies were available, then 
laboratory studies, design analogies, and other information [were] 
used to decide what value to place in the table. In all cases where 
the assigned protection factor changed when compared to the 1980 
standard, the assigned number is lower in the 1992 standard.

In addition, the 1992 ANSI Z.88.2 standard abandoned ANSI's 1980 
practice of giving increased protection factors to some respirators 
when quantitative fit testing was performed.
    Thomas Nelson, the co-chair of the ANSI Z88.2-1992 Subcommittee, 
published a second report entitled ``The Assigned Protection Factor 
According to ANSI'' (Ex. 135) four years after the Z88.2 Subcommittee 
completed the revised 1992 standard. In the report, Nelson reviewed the 
reasoning used by the ANSI Subcommittee in setting the 1992 ANSI APFs. 
Nelson noted that the Z88.2 Subcommittee gave an APF of 10 to all half 
mask air-purifying respirators, including quarter mask, elastomeric, 
and disposable respirators. The Subcommittee also recommended that full 
facepiece air-purifying respirators retain an APF of 100 (from the 1980 
ANSI standard) because no new data were available to justify another 
value. Nelson noted that the Z88.2 Subcommittee approved the RDL's 
reduction to an APF of 25 for loose-fitting facepieces and PAPRs with 
helmets or hoods based on their performance in WPF studies. For half 
mask PAPRs, the ANSI Subcommittee set an APF of 50 based on a WPF study 
by Lenhart (Ex. 1-64-42). The ANSI Subcommittee had no WPF data 
available for full facepiece PAPRs, so Nelson indicated that the 
Subcommittee selected an APF of 1,000 to be consistent with the APF for 
PAPRs with helmets or hoods. The Subcommittee, in turn, based its APF 
of 1,000 for PAPRs with helmets or hoods on design similarities (i.e., 
same facepiece designs, operation at the same airflow rates) between 
these respirators and airline respirators. Nelson noted that the 
results from a subsequent WPF report by Keys (Ex. 1-64-40) on PAPRs 
with helmets or hoods were consistent with an APF of 1,000. According 
to Nelson, the Subcommittee used WPF studies by Myers (Exs. 1-64-47 and 
1-64-48), Gosselink (Ex. 1-64-23), and Que Hee and Lawrence (Ex. 1-64-
60) to set an APF of 25 for PAPRs with loose-fitting facepieces. Nelson 
stated that two WPF studies, conducted by Gaboury and Burd (Ex. 1-64-
24) and Stokes (Ex. 1-64-66) subsequent to publication of ANSI Z88.2-
1992, supported the APF of 25 selected by the Subcommittee for PAPRs 
with loose-fitting facepieces.
    Nelson also stated in his report that the ANSI Subcommittee had no 
new information on atmosphere-supplying respirators. Therefore, the 
APFs for these respirators were based on analogies with other similarly 
designed respirators (Ex. 135). The ANSI Subcommittee based the APF of 
50 for half mask continuous flow atmosphere-supplying respirators, and 
the APF of 25 for loose-fitting continuous flow atmosphere-supplying 
respirators, on the similarities between these respirators and PAPRs 
with the same airflow rates. Nelson noted that the ANSI Subcommittee 
set the APF of 1,000 for full facepiece continuous flow atmosphere-
supplying respirators consistent with the APF for SARs with helmets or 
hoods using the results of two earlier studies: a WPF study by Johnson 
(Ex. 1-64-36) and a SWPF study by Skaggs (Ex. 1-38-3). The Subcommittee 
used the design analogy between PAPRs and continuous flow supplied-air 
respirators to select the APF of 50 for half mask pressure-demand SARs 
and an APF of 1,000 for full facepiece pressure-demand SARs. Nelson 
stated, ``The committee believed that setting a higher APF because of 
the pressure-demand feature was not warranted, but rather that the 
total airflow was critical'' (Ex. 135).
    Nelson noted in the report that the Subcommittee selected no APF 
for SCBAs. In explaining the committee's decision, he stated that ``the 
performance of this type of respirator may not be as good as previously 
measured in quantitative fit test chambers.'' Nelson also observed that 
the ANSI Z88.2-1992 standard justified this approach in a footnote to 
the APF table. The footnote states:

    A limited number of recent simulated workplace studies concluded 
that all users may not achieve protection factors of 10,000. Based 
on [these] limited data, a definitive assigned protection factor 
could not be listed for positive pressure SCBAs. For emergency 
planning purposes where hazardous concentrations can be estimated, 
an assigned protection factor of no higher than 10,000 should be 
used.

    A new ANSI Z88.2 Subcommittee recently finished revising the ANSI 
Z88.2-1992 standard, in accordance with the ANSI policy specifying that 
each standard receive a periodic review. This revised ANSI Z88.2 
standard is currently under appeal to the ANSI Board.

C. Need for APFs

    When OSHA published the final Respiratory Protection Standard in 
January 1998, it noted that the revised standard was to ``serve as a 
`building block' standard with respect to future standards that may 
contain respiratory protection requirements'' (63 FR 1265).

[[Page 50127]]

OSHA's final Respiratory Protection Standard established the minimum 
elements of a comprehensive program that are necessary to ensure 
effective performance of a respirator. The only parts missing from this 
building block standard are the APF and MUC provisions that are being 
finalized in this rulemaking. In the standard the Agency recommended 
that employers in the interim ``take the best information into account 
in selecting respirators. As it did under the previous standard, OSHA 
itself will continue to refer to the NIOSH APFs in cases where it has 
not made specific compliance interpretations'' (63 FR 1203).
    In October 2004, NIOSH published its Respirator Selection Logic 
(RSL), an update of the 1987 RDL. The APF tables in the new RSL have 
not changed from those in the 1987 RDL. However, NIOSH stated in the 
forward to the 2004 RSL: ``[w]hen the OSHA standard on APFs is 
finalized NIOSH intends to consider revisions to this RSL.'' (Ex. 20-
4.)
    The ANSI Z88.2-1992 APF table also has been a source for interim 
APFs while OSHA completed its APF rulemaking. However, the ANSI Z88.2-
1992 respiratory protection standard was withdrawn by ANSI in 2003. 
While a revised ANSI Z88.2 standard has been written, the final ANSI 
standard has yet to be published since it is currently under appeal. 
Therefore, no ANSI respiratory protection standard with recommended 
APFs is available at this time. The draft APF table from the ANSI Z88.2 
revision was submitted to the OSHA rulemaking docket (Ex.13-7-2), and 
was the subject of discussion during the public hearings on APFs. OSHA 
considered the draft ANSI table during its deliberations in this 
rulemaking.
    Throughout the Respiratory Protection Standard rulemaking, OSHA has 
emphasized that the APF and MUC definitions and the APF table are an 
integral part of the overall standard. A careful review of the 
submitted comments and information supports the Agency's conclusion 
that this final standard is necessary to guide employers in selecting 
the appropriate class of respirator needed to reduce hazardous 
exposures to acceptable levels. The final APF for a class of 
respirators specifies the workplace level of protection that a class of 
respirator should provide under an effective respiratory protection 
program. In addition, the APFs can be utilized by employers to 
determine a respirator's MUC for a particular chemical exposure 
situation.
    The final APFs must be used in conjunction with the existing 
provisions of the Respiratory Protection Standard. Integration of the 
final APF and MUC provisions into the reserved provisions of paragraph 
(d) completes that standard. With the addition of these provisions, 
appropriate implementation of the Respiratory Protection Standard by 
employers in their workplaces should afford each affected employee the 
maximum level of respiratory protection.

III. Methodology for Developing APFs for Respirators

A. Introduction

    In the proposed rule for Assigned Protection Factors (APFs), OSHA 
raised a number of issues or questions about its proposed methodology 
for deriving APFs (68 FR 34112-34113). OSHA asked for information on: 
(1) The evidence-based method used by OSHA in developing the proposed 
APFs; (2) any additional studies that may be useful in determining APFs 
that were not already identified by OSHA in the proposal; and, (3) 
statistical analyses, treatments, or approaches, other than those 
described in the proposal, available for differentiating between, or 
comparing, the respirator performance data. The vast majority of the 
comments in response to the NPRM addressed the use of WPF studies for 
establishing the APF for filtering facepiece half mask respirators. 
OSHA also received comments on the methodology and data it used for 
determining the filtering facepiece APF, and was provided with new 
studies on these respirators for consideration. OSHA's quantitative 
analyses for establishing the APFs for other classes of higher 
performing respirators drew little comment, and no new studies on these 
respirators were submitted. This section, therefore, focuses on 
methodology and new information relative to the APF for half mask air-
purifying respirators.
    More specifically, Part C of this section contains a discussion of 
the comments about OSHA's proposed methodology for determining APFs for 
filtering facepiece half mask respirators, including comments on data 
analysis and study selection. In addition, OSHA is providing an 
overview of Dr. Kenny Crump's statistical analyses (Ex. 20-1) of the 
updated half mask database (Ex. 20-2). Comments about alternative 
approaches are discussed in Part D (``Methodology, Data, and Studies on 
Filtering Facepieces and Elastomerics''). The Agency's overall 
conclusions on methodology, and summaries of new studies submitted 
during the public comment process, are presented under Part E. 
Discussion of the comments and opinions regarding the APF for half mask 
respirators and the establishment of the APFs for higher performing 
respirators is included in Section VI, Summary and Explanation of the 
Final Standard.

B. Background

    The Occupational Safety and Health Act of 1970 (``OSH Act''), 29 
U.S.C. 651-678, enacted to ensure safe and healthy working conditions 
for employees, empowers OSHA to promulgate standards and provides 
overall guidance on how these standards are to be developed. It states:

    (5) The Secretary, in promulgating standards dealing with toxic 
materials or harmful physical agents under this subsection, shall 
set the standard which most adequately assures, to the extent 
feasible, on the basis of the best available evidence, that no 
employee will suffer material impairment of health or functional 
capacity even if such employee has regular exposure to the hazard 
dealt with by such standard for the period of his working life. 
Development of standards under this subsection shall be based upon 
research, demonstrations, experiments, and such other information as 
may be appropriate. In addition to the attainment of the highest 
degree of health and safety protection for the employee, other 
considerations shall be the latest available scientific data in the 
field, the feasibility of the standards, and experience gained under 
this and other health and safety laws. Whenever practicable, the 
standard promulgated shall be expressed in terms of objective 
criteria and of the performance desired. 29 U.S.C. 655(b)(5) 
[emphasis added].

A reviewing court will uphold standards set under this section when 
they are supported by substantial evidence in the record considered as 
a whole (29 U.S.C. 655(f)). In searching for the ``best available 
evidence'' upon which to base its rulemaking, OSHA is required to 
``identify the relevant factual evidence, * * * to state candidly any 
assumptions on which it relies, and to present its reasons for 
rejecting any significant contrary evidence or argument.'' Public 
Citizen Health Research Group v. Tyson, 796 F.2d 1479, 1495 (D.C. Cir. 
1986).

    OSHA has retained the multifaceted approach it used in the proposal 
to determine the APFs for classes of respirators. That is, the Agency 
reviewed all of the available literature, including the various 
analyses by respirator authorities, as well as quantitative analyses of 
data from WPF and SWPF studies. During revision of the overall 
Respiratory Protection Standard, the Agency used a similar approach 
when reviewing protection factor studies related to the effectiveness 
and necessity of a comprehensive respiratory protection program.

[[Page 50128]]

    The Agency did not use Effective Protection Factor (EPF) and 
Program Protection Factor (PPF) studies in its APF analyses since these 
measure deficiencies in respirator program practices. More 
specifically, EPFs are not directly comparable to WPF values because 
the determinations include the time spent in contaminated atmospheres 
both with and without respiratory protection. PPFs are affected by any 
deficient elements of a respirator program, including inadequate 
respirator selection and maintenance, poor user training and 
motivation, work activities, and inadequate program administration. 
Therefore, OSHA relied on WPF and SWPF studies, since they focus on the 
performance characteristics of the respirator only.
    During the APF rulemaking, OSHA reviewed the extensive literature 
on APFs and developed selection criteria for including studies and data 
in its quantitative analysis of respirator performance. This procedure 
ensured that only carefully designed and executed WPF and SWPF studies 
were included in the analysis. The Agency then used these studies to 
compile the NPRM's original database. The database was comprised of 917 
data points from 16 WPF studies for half mask respirators (Matrix 1) 
and 443 data points from 13 studies for PAPRs and SARs (Matrix 2), 
conducted in a variety of American workplaces. OSHA made the studies, 
its selection criteria, the data, and its analyses available to the 
public electronically and through the rulemaking docket. In addition, 
the Agency encouraged the public to access this information and to 
reanalyze the data using methods of their choice. The Agency also 
sought submissions from the public of any additional studies for 
inclusion in its database. Four additional WPF studies of half masks 
were submitted during the public comment period following publication 
of the NPRM. Dr. Kenny Crump updated the Matrix 1 half mask database 
with these additional studies (Ex. 20-2) and reanalyzed the resulting 
1,339 data points for half mask respirators (Ex. 20-1).
    Dr. Crump also performed a second quantitative analysis in which 
the 1,339 accepted data points (original NPRM database updated with 
data from the four new studies) for half mask respirators were combined 
with 403 data points from 12 studies that the Agency originally 
excluded from the analysis. This second analysis corroborated the 
original findings to the extent practicable. The results of both of 
these analyses provide compelling support of OSHA's conclusions 
regarding the appropriate APF for half mask respirators. The Agency 
believes that the database it constructed represents the best available 
data on APFs, and that its conclusions are based on substantial 
evidence. See Texas Independent Ginners' Association v. Marshall, 630 
F.2d 398, 413 n. 48 (5th Cir. 1980), citing Industrial Union Dept., 
AFL-CIO-CIC v. American petroleum Institute, 448 U.S. 607, 661 (1980).
    In past rulemakings, OSHA's conclusions as to the best available 
evidence have been upheld as based on substantial evidence when it has 
relied on a body of reputable scientific evidence. See ASARCO v. 
Occupational Safety and Health Administration, 746 F.2d 483, 494 (9th 
Cir. 1984). OSHA need not accept all data presented to it as long it 
considers the data and rejects it on reasonable grounds. See id. 
Furthermore, each study relied upon by the Agency need not be a model 
of textbook scientific inquiry, and OSHA need not find one definitive 
study supporting its decision. Public Citizen Health Research Group, 
796 F.2d at 1489, 1495. Rather, the Agency is justified in adopting a 
conclusion when the cumulative evidence is compelling. Id. at 1489, 
1491, 1495. OSHA's conclusions are strongest when it has relied on 
multiple data sources that support each other, as it has in this 
rulemaking.

C. Methodology, Data, and Studies on Filtering Facepieces and 
Elastomerics

1. Comments on the Methodology
    OSHA developed the proposed APFs through a multi-faceted approach. 
As it stated in the preamble to the proposal, ``The Agency reviewed the 
various analyses of respirator authorities, available WPF and SWPF 
studies, and other APF literature.'' It later concluded that ``the APFs 
proposed by OSHA in this rulemaking represent the Agency's evaluation 
of all available data and research literature i.e., a composite 
evaluation of all relevant quantitative and qualitative information'' 
(68 FR 34050). OSHA then asked the public if this method was 
appropriate to determine APFs. The methodology was supported by a 
number of commenters, including NIOSH (Ex. 9-13), the Department of the 
Army (Ex. 9-42), ALCOA (Ex. 10-31), and others (e.g., Exs. 9-1, 9-4, 9-
14, 9-16, 9-22, 10-2, 10-17, 10-18, and 10-59). NIOSH stated:

    NIOSH agrees that the APF values resulting from this multi-
faceted approach are reasonable indications of the level of 
protection that should be expected for each class of respirators. * 
* *
    The available data are not ideal because there can be 
considerable model-to-model variation and only a few models in each 
class have been evaluated. Given that lack of complete data, the 
approach taken by OSHA is the most appropriate currently possible. 
(Ex. 9-13.)

    The United States Army Center for Health Promotion and Preventive 
Medicine commented:

    The method of APF development used by OSHA is appropriate. OSHA 
reviewed available data, both published and unpublished; utilized 
technical reviews and summaries from subject matter experts outside-
OSHA; weighed study findings and conclusions based on study 
shortfalls, as then state-of-the-art technical bias and procedural 
omissions; and used a conservative approach to maintain confidence 
that minimal risk of respirator selection and use errors will exist 
in worker protection from proposed APF use. (Ex. 9-42-1.)

    Nevertheless, some commenters did not agree with OSHA's approach. 
These participants included several labor organizations (Exs. 9-27, 9-
29, 9-34, 9-40, and 10-37), trade associations (Exs. 9-24 and 10-27), 
and individuals (e.g., Exs. 9-17, 9-25, 9-33, 9-41, 10-33, and 10-42). 
Criticisms of OSHA's approach focused on the Agency's selection of WPF 
studies for its determination of the proposed APFs. Reasons given to 
support these criticisms included: The differences between the studies 
do not permit comparison of the studies; the study conditions are not 
representative of typical workplaces; the study data are too old; the 
data do not cover all configurations of filtering facepieces available; 
and, the analytical method employed by some studies was too sensitive.
    A few commenters (Exs. 10-34 and 10-47) recommended that certain 
criteria should be met before a WPF study is deemed acceptable for 
analysis. These criteria include: Exposures to small particle sizes; 
work time of at least four hours; moderate to heavy work rate; and, 
high temperature and humidity. Still others believed that OSHA should 
develop and perform SWPFs on a representative subset of all filtering 
facepieces or all configurations of filtering facepiece respirators and 
all respirator models, and establish APFs for all classes of 
respirators based on the SWPF study results (Exs. 9-41 and 10-27). A 
more detailed discussion of data issues is presented below.
2. Comments on Data and Study Problems
    Selection bias in WPF studies. Several commenters stated that the 
authors of WPF studies ``cherry-picked'' either the workplaces in which 
the studies were

[[Page 50129]]

conducted or the individual tasks that were performed by workers chosen 
for monitoring (Pascarella, Tr. at 464; Faulkner, Tr. at 549 and 564-
565). ``Cherry-picking'' is a common term for ``selection bias.'' 
Selection bias is a matter of concern when either workplace study 
participants or job tasks are selected for inclusion in the study in a 
manner that skews the results of the study away from the true value.
    Selection bias is a matter of concern for all scientific studies, 
not just WPF studies, and peer reviewers typically evaluate its effects 
before a study is accepted for publication in a peer-reviewed journal. 
Most of the studies included in OSHA's analysis of WPF studies were 
either published in peer-reviewed journals or were presented at the 
AIHCE, and met the criteria for respirator research studies accepted by 
the industrial hygiene community. The half mask database consists of 16 
studies performed in a variety of workplaces over a range of years 
(from 1976 to 2004) by many different researchers. Therefore, it is 
highly improbable that these studies were subject to selection bias. 
OSHA could find no instance of selection bias either in its review of 
the scientific studies or its analysis of the data. Finally, OSHA 
repeatedly asked commenters who raised concerns about ``cherry-
picking'' for specific studies in which selection bias occurred. In no 
case did the commenters provide any details to support their 
allegations.
    Observer effect in WPF studies. Several commenters (Shine, Tr. at 
644 and Macaluso, Tr. at 652) stated that data from the WPF studies 
considered by OSHA were the result of a condition known as the 
``observer effect.'' The observer effect occurs when the act of 
observing or monitoring test subjects causes their responses to differ 
from their usual (nonobserved) responses. In some of the WPF studies 
used by OSHA, the researchers stated that during the study, they were 
present to monitor the test equipment to ensure that the sampling 
equipment functioned properly, thereby increasing the usefulness of the 
results. In other WPF studies, the researchers did not indicate their 
presence during the study.
    The mere presence of an observer does not, in and of itself, 
presume that there will be an observer effect. For example, if the 
observer is a researcher who is monitoring the test equipment instead 
of a supervisor who is monitoring the workers' practices, the workers 
are unlikely to change their practices.
    Although the Agency repeatedly asked the commenters who raised this 
concern to identify specific studies in which the observer effect may 
have been involved, they could not do so (i.e., in no case did the 
commenters provide any example to support their allegations). In its 
own analysis of the WPF studies, the Agency was also unable to find any 
evidence of an observer bias.
    Representativeness of the data. A number of commenters expressed 
concern that the study data analyzed by OSHA were not representative of 
conditions found in the construction industry (Ex. 9-29, Building 
Construction Trades Department), or of workplace conditions in general 
(e.g., Exs. 9-34, International Union Operating Engineers; 9-35, 
Melissa Rich; 9-40, United Steel Workers of America; and 10-60, Paul 
Hewett). The bulk of these concerns are represented in the comments of 
Melissa Rich, a Department of Energy respirator program manager, who 
stated:

    The selection of the test sites for the cited APF proposed 
rulemaking WPF studies are not representative of the worksite for 
American workers. Many test sites chosen for these studies were 
selected on availability only. Moreover, key study attributes such 
as hot humid conditions, long work hours, and heavy workload were 
the exception, not the norm for most of the cited studies. Most test 
sites had ambient concentrations less than the OSHA half mask 
respirator maximum use limit (i.e., ten times the PEL).
* * * * *
    The various particle sizes, a critical issue in a WPF, cited in 
many of the APF proposed rule Workplace Protection Factor studies 
are so large that they do not penetrate the faceseal. Many 
respiratory protection studies have indicated that particles larger 
than two microns are less likely to penetrate the most important 
attribute of a respirator, the faceseal. Most of the APF proposed 
rule Workplace Protection Factor studies have a particle size 
greater than two microns. (Ex. 9-35.)

    The studies analyzed by OSHA consisted of a varied cross-section of 
workplaces and conditions. For example, workplaces included ship 
breaking, asbestos removal, aluminum and lead smelters, brass 
foundries, and aircraft painting and manufacturing. Two of the four new 
studies analyzed by OSHA involved concrete-block manufacturing. The 
authors of an aluminum smelter study (Ex. 1-64-24) noted that employees 
were required to rest in a cool area for 50% of each hour due to high 
heat, and a steel mill study (Ex. 1-64-50) and a primary lead smelter 
study (Ex. 1-64-42) both were conducted in the sinter plant and blast 
furnace areas. The asbestos study (Ex. 1-64-54) was conducted under 
high humidity conditions. Tasks performed by test subjects included 
welding and grinding, torch cutting, pouring molten metal, handling 
concrete blocks, and spray painting. Work rates for these studies, when 
provided, ranged from low to heavy.
    The purpose of a WPF study is to evaluate a respirator's 
effectiveness under actual workplace use conditions. Consequently, the 
contaminant concentrations and particle sizes contained in the analyzed 
studies were generated while the workers performed their normal job 
duties. With regard to concerns about particle size, Myers et al. 
(Ex.1-64-51) found particles larger than 10 microns inside the 
respirator facepiece. The Agency believes that accepting only WPF 
studies that are conducted at exposure levels close to 10 times the 
PEL, with particulates of two microns in size or less, would not be 
representative of the conditions found in the workplace. Studies based 
on such selective criteria would be more akin to a SWPF, rather than a 
WPF, study. OSHA has concluded that the data used in its analyses are 
applicable to other American work settings because a range of work 
rates and environmental conditions were represented, and many of the 
tasks performed by the test subjects are performed in a variety of 
workplaces, including construction. Accordingly, the Agency is not 
persuaded by comments suggesting that the studies were so narrowly 
focused that the data cannot be applied to other work settings.
    Sensitive analytical method. Several commenters questioned the use 
of sensitive analytical methods for the analyses of workplace 
exposures, sometimes accompanied by a recommendation to test 
respirators under controlled laboratory settings, and at sufficiently 
high concentrations to obtain inside-the-facepiece measurements (Ci) 
that can be assessed by less sensitive methods (e.g., Exs. 9-32, 9-35, 
10-6, 10-37, and 10-49). The commenters believed that sensitive 
analytical methods (particularly PIXEA, proton-induced x-ray emission 
analysis) permit the determination of low Ci concentrations, resulting 
in high protection factors.
    In response to these comments, OSHA reviewed the seven half mask 
studies that used the PIXEA analytical method (Exs. 1-64-19, 1-64-51, 
1-64-52, 1-64-15, 1-64-16, and 1-64-34) and found that six of the 
studies used the method to measure both the Ci and Co concentrations. 
The seventh study (Ex. 3-12) used PIXEA to measure the Ci concentration 
but used atomic absorption (AA) to assess Co concentrations because the 
respirator filters were overloaded. However, the

[[Page 50130]]

Agency does not believe that this study provided inaccurate results. 
Under conditions of high Co concentrations, the AA method must be used 
because the PIXEA method would exceed its maximum measurement limits. 
Therefore, the PIXEA method would be unable to provide accurate Co 
data. Based on its review of these seven studies, the Agency found that 
the sensitive analytical method (i.e., PIXEA) allowed the investigators 
to quantify small amounts of contaminant that penetrate a respirator. 
This method permitted accurate assessment of Ci concentrations under 
conditions of low ambient concentrations, thereby permitting the use of 
actual Ci values in determining WPFs. Less sensitive methods would 
result in penetration values that are nondetectable or less than the 
limit of detection (LOD) for the analytic method, thereby requiring the 
study to discard these data or to correct for nondetected values using 
unvalidated statistical techniques. On the other hand, the sensitive 
analytical method was able to quantify low Ci concentrations, thereby 
enhancing the validity of the subsequent analysis by retaining the 
actual data and avoiding unvalidated statistical corrections.
    Craig Colton of 3M provided the following testimony in support of 
OSHA's conclusions:

    Some commenters also asserted that the use of analytical methods 
with low detection limits are a reason to invalidate some of the WPF 
studies. The claim is erroneously made that the analytical 
sensitivity affects the results from WPF studies. However, the 
actual amount of contaminant on the Ci sample is not changed by the 
analytical method.
    * * * Because the [Ci levels are] typically very small in a WPF 
study, the higher sensitivity of [the PIXEA method] is necessary to 
get the best data.
    * * * The WPF protocol from the AIHA Respirator Committee 
recommended the use of analytical methods with sensitive detection 
limits. * * * Use of less sensitive analytical methods for * * * 
[Ci] sample[s] that result in nondetect values are not meaningful 
for determining true exposure. (Tr. at 413-414.)

    In its post-hearing comments, 3M illustrated the value of sensitive 
analytical methods using the following example:

    [C]onsider three filters ``spiked with 1 [mu]g of silicon each 
and analyzed by three different methods [gravimetric, atomic 
absorption (AA), and PIXEA]. In the case of gravimetric and AA 
analyses, it is certain only that the silicon mass on the filter is 
between 0 [mu]g and 10 [[mu]g] or 0 [mu]g and 5 [mu]g respectively. 
However, PIXE[A] has sufficient analytical sensitivity to ``find'' 
the true value of 1 [mu]g. Because the mass of contaminants on a Ci 
filter is typically very small in a WPF study, the higher 
sensitivity of PIXE[A] is necessary to get the best data. (Ex. 19-3-
1.)

    Tom Nelson commented that ``[t]he analytical method must be 
sensitive for a WPF study. For a half facepiece respirator[,] the 
detection limit should be at least \1/100\ of the ambient 
concentration'' (Ex. 18-9). Later in these comments, Nelson stated, 
``The [low-concentration Ci] samples are part of the distribution of 
WPF samples collected during a study. These represent true measures of 
performance.''
    Based on the evidence in the record, OSHA concludes that using 
sensitive analytic methods for assessing Ci samples is both necessary 
and appropriate. Specifically, the Agency sees no scientific basis for 
excluding WPF studies that used PIXEA, particularly when using the 
method to determine both Ci and Co. The Agency's review of the record 
evidence shows that a leading national organization representing 
industrial hygienists (i.e., the AIHA) recommends using sensitive 
analytic methods for assessing Ci samples. Furthermore, using sensitive 
analytic methods improves significantly the validity of data analyses 
by allowing studies to retain low Ci values, and by reducing 
substantially the need to use unvalidated techniques to correct low Ci 
values. Therefore, OSHA concludes that the data from the WPF studies 
used in its analyses are accurate, and that the availability of data 
with low Ci values improved the validity of the APFs derived from these 
analyses.
    Large particles. Several commenters (e.g., Exs. 9-33, 9-35, 10-6, 
10-37, and 10-41) postulated that larger particles (greater than one or 
two microns) do not penetrate a respirator's faceseal. They believed 
that WPF studies having large particles in the Co concentration should 
be excluded from OSHA's analyses. They reasoned that these large 
particles were being measured as part of the Co but had no chance of 
being measured in the Ci, and consequently were inflating the WPF 
values.
    These commenters appear to be ignoring the possibility that half 
masks (both elastomerics and filtering facepieces) with faceseals that 
selectively filter large particles still are capable of providing an 
adequate level of protection. Nevertheless, OSHA notes that in one of 
the WPF studies used in OSHA's data analyses, Myers et al. found large 
particles (i.e., 10 microns in diameter) inside the facepiece, 
indicating that large particles are capable of penetrating a respirator 
faceseal (Ex. 1-64-51). Consistent with these results, Tom Nelson 
stated in his comments that ``[t]he particle size of contaminants in 
the various WPF studies in the docket rang